<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .text{
            color: red;
            font-size: 30px;
        }
        #desc{
            color: green;
            font-size: 40px;
        }
        .t1{
            color: red;
        }
        .t2{
            color:green;
        }

    </style>
</head>
<body>
    <h3>全局选择器：*</h3>
    <h3>元素选择器：标签名称</h3>
    <h3>类选择器：class属性名（.）</h3>
    <h3>ID选择器：id属性名（#）</h3>
    
    <p class="text" id="desc">我是p标签内容</p>

    <p class="t1 t2">我是测试文本</p>

</body>
</html>